Unit Tests Passed but Features Never Ran: A SwiftUI Developer's Recurring Blind Spot

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A solo developer building a SwiftUI iOS app for scoring restaurant reviews discovered that three separate features shipped in one session with all unit tests passing, yet none of the features ever executed in the live app. In each case, the failure stemmed not from buggy logic but from broken wiring — new arguments were either never passed at call sites or omitted from a field-by-field merge function, causing silent fallbacks with no crashes or error logs. One feature, a restaurant tenure analysis backed by 692 MB of public data and 15 passing tests, existed entirely within preview canvases and rendered zero pixels on a real device. Notably, the second and third failures occurred after the developer had already diagnosed the first and written a dedicated test file to catch exactly this pattern. The incidents highlight a structural gap where unit tests validate isolated logic but cannot detect missing wiring between components in a live execution path.

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